A photonic thermalization gap in disordered lattices

TL;DR

This paper reveals a photonic thermalization gap in disordered lattices with chiral symmetry, where input light cannot access sub-thermal photon statistics, enabling deterministic control of photon statistics through input field shaping.

Contribution

It introduces the concept of a thermalization gap in disordered photonic systems with chiral symmetry and proposes a method for controlling photon statistics via input field manipulation.

Findings

Sub-thermal photon statistics are inaccessible in these systems.

Input coherent light always results in super-thermal statistics at steady state.

Controlled excitation-symmetry-breaking enables tuning photon statistics.

Abstract

The formation of gaps -- forbidden ranges in the values of a physical parameter -- is a ubiquitous feature of a variety of physical systems: from energy bandgaps of electrons in periodic lattices and their analogs in photonic, phononic, and plasmonic systems to pseudo energy gaps in aperiodic quasicrystals. Here, we report on a `thermalization' gap for light propagating in finite disordered structures characterized by disorder-immune chiral symmetry -- the appearance of the eigenvalues and eigenvectors in skew-symmetric pairs. In this class of systems, the span of sub- thermal photon statistics is inaccessible to input coherent light, which -- once the steady state is reached -- always emerges with super-thermal statistics no matter how small the disorder level. We formulate an independent constraint that must be satisfied by the input field for the chiral symmetry to be `activated' and the gap to be observed. This unique feature enables a new form of photon-statistics interferometry: the deterministic tuning of photon statistics -- from sub-thermal to super-thermal -- in a compact device, without changing the disorder level, via controlled excitation-symmetry-breaking realized by sculpting the amplitude or phase of the input coherent field.